This invention relates to a central processing unit of a computer suitable for use in structured programming.
In recent years, so-called structured programming has been used for the purpose of improving the productivity of software. Heretofore, however, how to increase the efficiency of execution of a program has been considered from the standpoint of programming technique and only a limited effort has been made to improve a central processing unit for executing structured programming and which is capable of readily preparing a program written with assembler language in a structured configuration where a plurality of blocks are assembled in a tree like structure. In this specification, the term "block" is used to mean an assembly of a minimum number of instructions and data that performs certain function and comprises one or more instructions, and the term "program" to mean an assembly of one or more blocks providing certain performance. Especially, in a computer, such as a micro-processor which is not provided with a suitable compiler enabling structured programming, the programmer must directly convert machine instructions into code by using an assembler. Therefore, it is desired to provide a novel central processing unit utilizing machine instructions for preparing structured programs.